The present invention relates to a valve for underwater aqualung supplying devices.
The valve of the invention includes:
a pressure chamber and a watertight compensation chamber, adjacent and watertightly separated by a partition wall,
a shutter including a tubular stem inserted, at least in part, inside each chamber,
the pressure chamber being provided with means to connect it to a pressurized gas source and with a housing suitable for cooperating with an end connected with the shutter,
the compensation chamber being provided with at least one opening communicating with the outside and contains a stem end in the shape of an expansion enlarged head connected with the valve outlet, and
a coil spring positioned into the compensation chamber between the expansion head and the partition wall,
the enlarged expansion head of the shutter being encircled by a thermal insulating annular part watertightly positioned between said head and the side wall of the compensation chamber.
A valve of this kind is known from the document EP 0811549 A. In this known valve the thermal insulating annular part is formed by an annular sealing ring on a greater diameter at the shutter""s enlarged end head.
In valves of this type, the supplied gas passing through the shutter expands into the expansion enlarged head zone, causing a remarkable cooling of said head and the shutter tubular stem, up to very low temperatures and next to the water freezing temperature. The construction of the known valves allows a thermal exchange between the coil spring and the expansion head and between the shutter tubular stem and the compensation chamber interior. The cooling extends then to the compensation chamber too. In the valves for underwater aqualung supplying devices, in particular in the first stages of the two phase supplying devices, the compensation chamber is filled with water in substantially stable conditions within. The cold transmission, especially from the shutter expansion head, can produce the freezing of the water in the compensation chamber, causing a following inefficiency when not blocking a valve, due to the blocking of the shutter motion.
The goal of the present invention is to provide a valve for underwater aqualung supplying devices to eliminate the disadvantages of the previously described known valves, and where the shutter thermal insulation is improved beside reducing the weight of the same, improving the lubrication within the chamber keeping the mechanical resistance characteristics unchanged.
This goal is achieved by the present invention through a valve for underwater aqualung supplying devices, characterized in that the thermal insulating part covers the expansion head and is positioned between the shutter head and the compensation chamber""s side wall through two or more watertight rings.